1. Field of the Invention
The present invention relates to an existing pipe rehabilitation method for rehabilitating existing pipes by linking a plurality of segments in the circumferential direction and pipe length direction to assemble a rehabilitating pipe inside the existing pipe.
2. Description of the Related Art
There are pipe rehabilitation methods known in the art in which a plurality of segments is linked in the circumferential direction and pipe length direction to assemble a rehabilitating pipe when sewerage pipes, waterworks pipes, agricultural water pipes, and other existing pipes have aged. A filler is used to fill the space between the rehabilitating pipe and existing pipe so as to integrate both the pipes together and construct a composite pipe (JP-A-2003-286742 and JP-A-2005-299711).
The rehabilitating pipe segment is an assembly unit for a rehabilitating pipe and comprises an internal surface plate, side plates, and end plates, these plates being integrally molded from a transparent or nontransparent plastic material in the form of a block. Reinforcing plates and ribs are preferably provided to increase the strength of the segment.
To link the segments in the pipe length direction, liking members are used which extend along the pipe length direction over both the side plates. The linking members are fixed to the segments and mutually linked to couple the segments together in the pipe length direction (JP-A-2005-299711).
In a method for linking segments as disclosed in JP-A-2005-299711, the linking members are mutually linked in the pipe length direction to produce a single long connected rod-shaped member. However, the segments cannot be coupled in the pipe length direction with sufficient strength at locations where no linking member exists, thus causing a problem that the coupling strength is different in the circumferential direction.
Using many segments as viewed in the circumferential direction of the segment enables the coupling strength to be uniform and to be increased. However, this disadvantageously increases man-hours and costs.